1. Field of the Invention
The present invention relates to a musical tone signal generating apparatus which generates a musical tone signal by effecting a modulation operation on waveform information inputted thereto.
2. Prior Art
The conventional apparatus (as disclosed in Japanese Patent Laid-Open Publication No. 62-83795) provides plural input terminals to which input information is supplied, modulation operation units for carrying out a modulation operation based on the input information and plural memories. The memories memorizes the operation results (i.e., waveform information) of the modulation operation units. By changing over the connection between each modulation operation unit and each memory in time-sharing manner, this conventional apparatus carries out the waveform operation based on the predetermined algorithm.
In the above-mentioned conventional apparatus, by arbitrarily varying the output level of first-stage modulation operation unit, the input level of second-stage modulation operation unit is to be adjusted.
As the input information of each modulation operation unit, it is possible to use the waveform information which is operated by the former-stage modulation operation unit and then stored in the memories and other waveform information to be obtained from the feedback line to which the waveform information of the latter-stage modulation operation unit is applied. Then, each modulation operation unit carries out the modulation operation on the mixture or selected one of the above-mentioned waveform information and other input information.
As described above, in the conventional apparatus, the input level of the latter-stage modulation operation unit is adjusted by varying the output level of the former-stage modulation unit. This configuration is advantageous when the operation result of former-stage is used as the input of one latter-stage. However, it is disadvantageous when the operation result of former-stage is used as the inputs of plural latter-stages. In such case, the conventional apparatus cannot adjust the input level of each modulation operation unit independently.
Further, as the input information of each modulation operation unit, the conventional apparatus can use the mixture or selected one of the waveform information outputted from the former-stage modulation operation unit and other waveform information to be obtained from the feedback line to which the waveform information of the latter-stage modulation operation unit is applied. However, it is impossible to use the arbitrary combination of the above-mentioned waveform information as the input information of each modulation operation unit.